Heretofore it has been accepted practice to provide, in carburetor structures, a power fuel enrichment system comprised of a power valve assembly carried by the carburetor in a manner so as to be effected by engine manifold vacuum. The manifold vacuum acting on a moveable pressure responsive member, which is adapted for operative engagement with the valving means of the power valve assembly, at idle or normal load conditions, as well as during engine deceleration, is strong enough to overcome a spring resistance so as to maintain the valving means closed. When high power demands place a greater load on the engine and manifold vacuum drops below a predetermined value, the said spring overcomes the reduced vacuum thereby opening the valving means. Consequently, fuel flows through the open valve means and ultimately into the carburetor induction passage thereby enriching the otherwise normally-provided fuel air mixture. As engine demands are reduced manifold vacuum again increases. The increased vacuum acts on the pressure responsive member to finally overcome the resistance of the said spring thereby closing the valving means and shutting off the added supply of fuel which is no longer required.
Because of governmentally imposed limitations on engine exhaust emissions and also governmentally imposed requirements for minimizing fuel consumption, it has often become practically impossible to provide a power valve assembly in a configuration as heretofore proposed by the prior art. That is, in order to meet such governmentally imposed limitations and requirements it has become necessary to add, for example, many different controls, passages and related structure to the otherwise conventional carburetor and, in so doing, it often becomes the case that there is less than adequate space available for the installation of the associated power valve assembly including its motor portion. It has often been found that in attempting to employ prior art power valve assemblies in present-day carburetor assemblies, the lack of adequate space dictates an overall power valve assembly which may have performance characteristics less than totally desirable.
Accordingly, the invention as herein disclosed and claimed is primarily directed to the solution of the preceding as well as other related and attendant problems.